The invention relates to electric motor driven watercraft and particularly to hull configurations made possible by application of hidden log technology to watercraft.
Private consumer watercraft used for fishing, cruising, waterskiing and the like typically are less than 30 feet long, most often less than 24 feet long, and can be pulled on a trailer behind a car for inexpensive boating. Such a watercraft generally has a displacement hull and is powered by an air-breathing fossil fueled motor connected to a fuel tank that holds a hydrocarbon high energy density power source. The hull displaces water when at rest and generally must be raised above the water surface to achieve high speed operation. Energy for this purpose is created from noisy explosions from within a high horsepower motor located at one end of the vessel hull, if the boat is a traditional outboard design, or perhaps from an engine within a hull that drives an impeller, as used in modem jet skis designs. Such pleasurecraft achieve high speed by virtue of advances in hull design and in high output fossil fueled motors.
The basic hull design of a fast pleasureboat having one or two attached motors has undergone little modification over the years. Many performance advances arose from simply increasing motor(s) size. In fact, early in the last century internal combustion engine powered watercraft became dominant and displaced electric powered watercraft because of their higher output to weight ratio (including the power source). That is, large horsepower engines became available to supply massive amounts of energy needed to lift up the weight of the boat (including the low weight hydrocarbon fuel supply), allowing high speed but low efficiency hydroplaning operation. Electric boats in contrast, have smaller motors with heavy batteries and generally are unable to match the speed and duration performance of the internal combustion powered pleasurecraft.
Other advances in the pleasureboat art arose from changes in hull configuration for increased operator convenience and/or speed. A representative improvement in this regard is described in U.S. Pat. No. 6,116,182. As summarized in that patent the floor of a boat hull may be altered for carrying passener(s) with a xe2x80x9craised after section that rises above the level of the deck platform . . . xe2x80x9d and using xe2x80x9ca downwardly sloped surfacexe2x80x9d to facilitate rider comfort and related changes to a hull that remains at the surface of the water when not moving. Boat hull improvements over the years have included among other things, easier entry and exit into the boat, streamlining the bathtub-like wall of the boat, and increasing watercraft stability by adding floatation.
Unfortunately for those interested in advantages of quiet electric propulsion, most developments relate to high power output internal combustion engine powered watercraft. Electric powered practical planing boats appear out of reach for the pleasure boat market. In fact, electric powered pleasurecraft less than 30 feet long designed for cruising are thought to be restricted to hull displacement speeds of less than 10 miles per hour. As we have described in an earlier filed application, multi-hulled ships such as pontoon boats and catamarans, and SWATH type craft, offer alternative designs, but have serious drawbacks, particularly in the context of smaller pleasurecraft that are driven by electric motors.
During their experimentation and design activities in challenging the low speed paradigm for electric boating the inventors made several discoveries that provide advantages to electric motor driven pleasurecraft with heavy power supplies. These advantages include, among others, increased speed, efficiency, stability, and operator convenience, as described below.
One embodiment of the invention is an electric motor driven watercraft comprising an upper platform with walls connected beneath to one or two submerged support members and one or two floating skis wherein the walls have egress openings on their starboard and port sides for easy boarding without stepping over a wall, the one or two support members provide buoyancy yet are completely submerged and positioned lateral to the floating skis and each contains an electric motor, and wherein the skis contain floatation that provides buoyancy to maintain watercraft stability during rest.
Another embodiment is an electric motor driven watercraft comprising an upper platform held above the water surface by a distance D and connected beneath to one submerged support member having an electric motor and to two floating skis, wherein the support member is located below, parallel and between the skis, and wherein the skis protrude forward of the platform by distance D and protrude rearward of the platform by distance D.
Another embodiment is an electric motor driven watercraft comprising an upper floating platform connected beneath to two elongated support members, one on each side of and below the platform, wherein each support member comprises an electric motor and propeller and provides buoyancy or lifting force to lift the platform during forward motion, and wherein the platform floats on the water surface during rest but is propelled forward by action of the electric motors.
Another embodiment is a wave dampening watercraft comprising a platform, a submerged support member attached underneath thereto having at least 25 percent of the empty watercraft mass, and two skis attached beneath the platform wherein the linkage between the platform and the skis comprises a shock absorber that absorbs wave energy colliding with the skis. In a preferred embodiment the shock absorber regenerates electrical energy to recharge batteries used to drive the watercraft.
Another embodiment of the invention is an electric motor driven watercraft less than 30 feet long comprising an upper platform held above the water and connected beneath to at least one ski and to at least one support member, wherein each support member comprises a power source and electric motor and provides positive buoyancy to hold up the platform, and wherein each skis has floatation that helps hold up the watercraft above the water surface during rest and is positioned above the support member but below the platform and provides stability against pitch and roll tendencies during forward motion and wherein the power source and electric motor combined account for at least 10 percent of the watercraft mass.
Another embodiment of the invention is an electric motor driven watercraft comprising a platform held up from the water surface through a distance D by buoyancy from a submerged support member located underneath the platform and by two floating skis located parallel to and on either side of the platform, wherein the floating skis are buoyant, are positioned underneath the platform by distance D but above the submerged support member, provide lateral stability to the platform during rest and wherein each floating skis extends both in front of and to the rear of the length of the platform surface that is accessible to passengers by a distance of at least D.
Yet another embodiment of the invention is an automated electronic steering device for watercraft comprising a plurality of terrestrial magnetic field sensors, wherein at least two sensors detect progressive deviation from a desired course, the progressive deviation sensors provide power adjustment signals to at least one electric motor that affects the watercraft direction of travel, and wherein the magnetic field sensors are mechanically held in a fixed position in a platen that is rotated to select a desired direction.